A scissors truss is a commonly used component in the manufacture of mobile homes wherein a series of such trusses are spaced from each other and conventionally connected to form a roof. A scissors truss of a type to which the present invention is concerned comprises a pair of inclined top chord members connected to a pair of inclined bottom chord members with generally vertical and inclined strut members extending therebetween. The top and bottom chords and the strut members are all preferably made from standard wood two-by-fours (2.times.4s) connected together in one plane. More specifically, adjacent inwardly directed upper ends of the top chords are connected together with rectangular metal connecting plates to form a top apex joint. Adjacent inwardly directed upper ends of the bottom chords, spaced vertically below the top apex joint, are also connected together with rectangular metal connecting plates to form a lower apex joint. One or more center vertical strut members connect the upper and lower apex joints together. Outwardly directed ends of associated top and bottom chords (i.e., located on one side of the center struts) connect together with rectangular metal plates to define heel joints. The vertical members extend from intermediate portions of the top chords to connect via rectangular plates to intermediate portions of the bottom chords. Inclined strut members may also extend from joints formed with the top chords to the base of the central vertical member or members forming the lower apex joint with the bottom chords.
The metal rectangular connector plates are each provided with a multiplicity of closely spaced teeth or projections punched out of the sheet metal which may be 18 gauge sheet steel, galvanized if desired. The projections are preferably generally triangular and are struck out substantially at right angles to plane of the plate so that they readily penetrate the fibers of the top and bottom chords when pressure is applied normal to the outer surface of the plate. Each projection forms a substantially rectangular slot in the plate and the size of the projections and their density per square inch of plate may be configured and arranged in the plate similarly as the teeth of the connector plates in, for example, U.S. Pat. No. 2,877,520 of common assignee herewith. The teeth are distributed over the major portion of the areas of the plate and these teeth provide structural securement for the ends of the chord members when embedded therein to form the top and bottom apex joints and the other joints discussed supra.
With a scissors truss utilized as a prefabricated roof truss in the manner described above, it is important that the standard connector metal plates described supra remain elevationally below the upper edge surfaces of the top chords to which upper edge surfaces roofing material will be flushly secured. Similarly, it is important that the rectangular truss connector plates remain elevationally above the lower edge surfaces of the bottom chords against which lower edge surfaces ceiling material (e.g., acoustical tile) will be flushly secured during final assembly of the mobile home. Because these edge surfaces are inclined with respect to the horizontal, the conventional rectangular layout of the standard truss connector plates do not permit a sufficient number of teeth to become embedded in the chords. Thus, the top and bottom apex joints may not have sufficient strength to conform to local code requirements unless these joints are strengthened either with reinforcement lumber and/or additional connector plates. Alternately, or in conjunction therewith, it is possible to mitre the ends of the chords forming the top and bottom apex joints for improved joint efficiency. However, whether the joints are strengthened either with mitred ends, reinforcement lumber and/or additional conventional rectangular connector plates, there results an inefficient use of lumber and/or labor, unnecessarily increasing the cost of the prefabricated scissors truss.
It is accordingly one object of the present invention to provide a scissors truss having top and bottom apex joints of a type employing novel forms of connector plates with struck teeth wherein the number of teeth embedded in the chords in the area of the joint are sufficient to provide improved joint efficiency vis-a-vis conventional rectangular connector plates with struck teeth.
It is another object of the present invention to provide a joint in a scissors truss of the type employing a novel form of connector plates with struck teeth which connector plates in the top and bottom apex joints are capable of carrying structural loading in final assembly of the scissors truss in single or double mobile homes.
Still another object of the present invention is to provide a novel form of connector plate for use in fabricating top and bottom apex joints of a prefabricated scissors truss and which novel form of connector plate may be universally used with different sizes of scissors trusses wherein truss size is dictated in accordance with varying state and local road height and width clearance limitations.
Yet a further object of the present invention is to provide a method of manufacturing a novel form of connector plate for use in fabrication of top and bottom apex joints within a scissors truss.
These and further objects and advantages of the present invention will become more apparent upon reference to the following specification, appended claims and drawings.